Servicing Your Car’s Throttle Body

Automobile innovation has come a long way. Today we have smarter cars with computers in the form of Engine Control Units (ECUs) which regulate a lot of settings that had to be adjusted manually on older cars with carburetors. Your car’s idling is one such example. These new, smarter cars make the vehicle technically more stable but they do bring about the element of sensitivity with them because to have this ‘intelligent’ system in place is only possible with the help of more complex mechanical parts and sensors (which were rare or absent altogether in the old cars).

The Throttle Body:

Plays a significant part in how well tuned the car is and how well it performs. It receives the signal from the throttle pedal (depending on how you press it) and lets in the amount of air accordingly which is to be mixed with the matching amount of fuel (electronically done through injectors from the signals transmitted by sensors). Since the throttle body plays this vital role in performance of the engine, it is important that its clean and free from gunk and dirt, and operates freely, with a fluid movement and is responsive (the hinges are free and don’t have excessive friction). The connected sensors and the IACV are also to be clean and serviced for optimal functionality.

Idle Air Control Valve(IACV) and IACV Sensor – This is the valve that is responsible for idling of your car (revving while your car is in a stationary position). Often a dirty or irresponsive IACV leads to idling problems which are a big bother. So the idea is to clean this valve nicely with a carb cleaner spray – readily available. Equally important is the IACV sensor – which operates the valve based on the signal it receives, and transmits the signal back to the ECU as well. This must also be cleaned.

MAP Sensor: Manifold absolute pressure sensor – Provides the ECU with information about the manifold pressure which allows it to calculate the density and rate of flow of the air into the engine and therefore allowing it to determine how much fuel is required for optimum combustion.

Air Temperature Sensor – Since cold and hot air combust with different intensity, it is important for the ECU to know what the air temperature is for the air coming into the throttle body.

Following is a pictorial DIY of servicing the throttle body, IACV and cleanup of the attached sensors:

Throttle Body Service

First, disconnect all attached sensors by unplugging their harnesses. These will include the MAF sensor (placed on the air intake pipe), the MAP sensor (placed on top of the throttle body – also in this image), TPS or throttle position sensor (placed behind the throttle body) and the IACV sensor (this is placed underneath the throttle body in A/T version of this civic).

Then you take out the intake pipe. disconnect it from the one end connected to the throttle body and the other one to the air cleaner housing.

Here is a view with the intake pipe disconnected;

Now a challenge in removing the throttle body was to remove these two cables that are attached to the fly on the throttle body.

The first one is detached;

The CNG venturi is removed by unscrewing two screws which fastened it to the throttle body.

This is the second cable, removing it was a bit of a challenge as I had to unscrew the metal plate which was attached to the throttle body. It came out after I did that.

A shot of the dirty and gunky throttle body. If you notice the top two corners are unscrewed, there was a bolt on one and a nut on the other. I then went on to unscrew the two at the bottom.

And here you can see the throttle body disconnected from the intake manifold. However, there are still two water pipes connected at the bottom of the throttle body, had to disconnect those before I could take it out.

These are the pipes below that had to be disconnected, and water poured out when once I disconnected them.

Throttle body was detached and I stuffed the intake manifold with a clothe to avoid dust or anything from going in.

You can see the bottom of the throttle body in the picture below, this is the solenoid to which attached with a lot of screws is where the IACV is and that plastic thing sticking out is the IACV sensor.

AFTER removing all the sensors attached to it (these were: MAP, TPS and IACV sensors) I began to clean up.

Items used to clean up the throttle – a tub, all my tools, petrol, WD40 and a tooth brush(to clean the groves). For your hands, always use gloves to easily wash them clean.

I tried to open up the IACV but the screws on it were stuck and didn’t move so I just poured in petrol and WD40 from the inside of the throttle body into the IACV and cleaned it up that way.